Security Advisories for Firefox ESR

Impact key

Critical
Vulnerability can be used to run attacker code and install
software, requiring no user interaction beyond normal browsing.

High
Vulnerability can be used to gather sensitive data
from sites in other windows or inject data or code into
those sites, requiring no more than normal browsing actions.

Moderate
Vulnerabilities that would otherwise be High or Critical
except they only work in uncommon non-default configurations or
require the user to perform complicated and/or unlikely steps.

Low
Minor security vulnerabilities such as Denial of Service
attacks, minor data leaks, or spoofs. (Undetectable spoofs of
SSL indicia would have "High" impact because those are generally
used to steal sensitive data intended for other sites.)